Start with the component list
For a gate valve, the controlled list normally includes wedge seating surfaces, body seat surfaces, stem and backseat. For a globe valve, it includes disc seating surface, body seat surface, stem and backseat. Check-valve trim follows its piston or disc and seat construction.
Packing, body-to-bonnet gasket, bearings, hinge pin, bolting and operator parts may sit outside a formal trim number. They still need materials where service or project specifications control them.
| Field | What to state | Why it matters |
|---|---|---|
| Body seat surface | Base material, overlay or hardfacing and minimum finished thickness if controlled | Corrosion, erosion, wear and shut-off |
| Closure surface | Wedge, disc or piston material and seating-surface treatment | Material pairing, hardness and galling |
| Stem | Material, condition and surface treatment | Strength, corrosion, galling and packing interface |
| Backseat | Material and surface treatment where fitted | Temporary stem-sealing interface and maintenance practice |
| Packing and gasket | Material and construction outside the trim shorthand | Temperature, emissions and chemical compatibility |
Trim numbers need a written material breakdown
Industry trim tables assign combinations of stainless, nickel alloy and hardfacing materials to numbers. The applicable table and edition must be named. A project-specific trim schedule or manufacturer table can differ in wording, product form or hardfacing process.
FerraForge’s technical source set records seat surface, closure surface, stem, backseat and a note for each published linear-valve trim code. Those fields should be repeated on the quotation and approved datasheet. The number remains an index, not the only material description.
Match materials to the damage mechanism
Corrosion resistance is only one criterion. Seating surfaces can suffer erosion, wire drawing, cavitation, flashing damage, adhesive wear, fretting or galling. Solids, high differential pressure and frequent cycling can justify hardfacing even where the base alloy resists the fluid.
Material pairs require attention. Two similar stainless surfaces under high contact load can gall. A hardfaced seat against a softer closure surface behaves differently from hardfacing on both surfaces. State which surface receives the overlay; do not reduce the requirement to a trade name.
Temperature and fluid data control the choice
Provide normal and design temperature, pressure, differential pressure at closure, medium composition, solids, phase and operating frequency. For sour oil-and-gas service, supply the environmental limits required for a review against ISO 15156 or the project’s NACE basis. Hardness restrictions can affect stem and seating choices.
For throttling globe valves, include every flow case. High local velocity can damage a material that performs well in static corrosion service. For check valves, unstable movement can wear guides, hinge parts and seats.
Verification must match the specified feature
A base-material certificate does not verify a deposited hardfacing layer. Where overlay chemistry, thickness, hardness or procedure is controlled, list the required records and inspection method. PMI, hardness testing, ferrite measurement and coating-thickness checks answer different questions.
Confirm certificate scope before order. EN 10204 3.1 or 3.2, PMI, hardness records and NDE are project options; they are supplied only when included in the agreed quotation and inspection plan.
Specification checks
- Give the trim table source and edition when a trim number is used.
- List seat, closure, stem and backseat materials in words.
- Identify hardfacing alloy, location, finished thickness and hardness where controlled.
- Provide fluid, temperature, differential pressure, solids and cycle frequency.
- State certificate, PMI, hardness and overlay-record requirements before manufacture.
Catalogue and RFQ
Standards publisher references
Published by Nordic Valves Ab Oy, the operator of FerraForge. These links describe the publishers’ official scope. Purchase documents must state the edition required by the project and include any amendments or owner specifications.
- API Monogram and APIQR programme documentsAmerican Petroleum Institute · Official standard titles and the API Monogram programme document register.
- ASME B16.34 - Valves - Flanged, Threaded, and Welding EndASME · Official scope covering valve pressure-temperature ratings, materials, dimensions, testing and marking.
- ISO 15156-2 - Carbon and low-alloy steels for H2S-containing oil and gas environmentsInternational Organization for Standardization · Official scope for selection and qualification of carbon and low-alloy steels against H2S-related cracking in the stated upstream environments.
- ISO 15156-3 - CRAs and other alloys for H2S-containing oil and gas environmentsInternational Organization for Standardization · Official scope for selection and qualification of corrosion-resistant alloys and other alloys in the stated upstream environments.